In the context of digital transformation in education, developing students’ digital competence through Informatics education has become increasingly important. However, classroom practice shows that many students may be able to perform software operations but still experience difficulties in applying technology to solve real-world problems. In response to this issue, the present study employs design-based research to propose a set of principles and a process for organizing project-based learning in high school Informatics education. The findings structure the project-based learning process into four stages and map these stages onto the six digital competence domains specified in Circular No. 02/2025/TT-BGDĐT. In addition, the study develops an illustrative project design for Grade 11 students and proposes an assessment rubric to support the identification of learners’ levels of digital competence development. Accordingly, the study provides a systematic and practically applicable reference model for secondary school teachers in the context of innovation in Informatics teaching.